


De-Stressed

by Athene



Category: Undertale (Video Game)
Genre: Alternate Universe - Underfell (Undertale), Light Bondage, M/M, Magical Drugs
Language: English
Status: Completed
Published: 2019-01-23
Updated: 2019-01-23
Packaged: 2019-10-14 20:04:08
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 836
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17515109
Author URL: https://archiveofourown.org/users/Athene/pseuds/Athene
Summary: Gaster tests a magical relaxant on Grillby in a decidedly unscientific manner.





	De-Stressed

**Author's Note:**

> Rated T for suggestive themes and magical drugs. Also general Underfell stuff because ... Underfell.

He depresses the plunger with all the distant pensiveness of a doctor.

Perhaps not the best of metaphors.

Certainly, he was a doctor in the most literal sense of the term, but there was a time and place for such roles.

Straddling a tied-down elemental in the middle of the night seemed like a poor choice in either respect.

Dark violet flames fan hot around him, the sheen of sweat on his brow ridge growing longer from the extended exposure. The willingness of his partner shows in the lack of damage done to both himself and his clothes--an impressive display of concentration when something so foreign flows into his magical form.

He smirks as he watches the expected change, dark flames flickering brighter as color spreads from the injection spot like rippling waves. A shuddering sigh from his patient accompanies the change, and he places the needle in the care of one of his summoned hands to deposit it on the bedside table. There is vague, morbid fascination in his eyelights as he settles again on top of his fiery partner, watching orange flames dance around and through the holes in his hands.

The color is not unusual for the landscape of Hotland, but very out of place in the darkness of Grillby’s bedroom.

“So this is how you are when you’re relaxed.” A thoughtful hum escapes him as he considers the other chemical mixtures that he had brought along. Concocting something that could act as a relaxant in an elemental had been an interesting challenge.

“Like what you see?” That jagged grin is familiar, even framed by oranges and yellows that spark thoughts of the warmth of a fireplace instead of the inherent dangers of the Underground. A wispy chuckle accompanies the grin, only somewhat strained by the way Grillby’s arms are tied to the headboard.

The ropes are barely a restraint for the fire elemental. In truth, he’s just self-centered enough that he wants to watch his own flames flicker to cooler hues; he’d even said as much as he placed his wrists together in smarmy acquiescence.

“The experiment yielded a result supported by my hypothesis.” His response is just south of the deadpan sarcasm border, made all the more obvious by his bored glance. He lets silence drift between them, considering the other mixtures he had placed by the bedside. “How do you feel?”

That was the entire point of this venture, after all: ensuring that Grillby could still reach those lower, less intense temperatures after decades of this ‘kill or be killed’ regime. Several monster types had evolved magical features to better survive the rough environment, while others relied on personal and professional connections to make up for physical deficiencies.

The most successful monsters were those that fell under both categories.

Many flame-based monsters evoked stronger displays of their element, turbulent and intense in similar hues as the Snowdin bartender. Burning hotter without any relief had resulted in an increase in Falling Down reports, much to the chagrin of fire monsters that were on their way to making Hotland a living hellscape. Things had not escalated after those reports were made public, but the numbers remained high in comparison to other monster types.

“I’m not complaining.” Grillby leans back and shuts his eyes, seeming to bask in the forgotten feeling of being able to relax the entirety of his magical form.

“That’s very unhelpful.” Gaster lifts one hand to flick his knuckle against his partner’s chin. He has to get a thorough writeup on the mixture’s effects if he wants to pursue further research. “I’m not doing this for free, you realize.”

A crackling chuckle is all the response he receives, and Gaster musters up the energy to glare for a moment. But the moment passes without further comment, and he shifts his attention to the feeble bindings that kept Grillby’s arms out of the way while he worked. In vague pettiness, he props a bony elbow on the other monster’s chest while he undoes the rope, tossing the short length off the bed without fanfare.

His reward is swift and sure--warm hands along the curve of his spine, fingers catching vertebrae in as intimate a caress as they could manage with the thin barrier of his shirt. Gaster shivers despite the heat, barely sparing himself an ungraceful fall onto Grillby’s torso.

The white eye that opens to peer up at him is _almost_ apologetic. “You can get your data another night, can’t you?”

Gaster sighs, meeting that gaze as he makes a begrudging admission. “Anything captured tonight is already informal and biased at best. At most, I’ll be able to measure how quickly you burn through a single dose.” He slides a hand up to Grillby’s cheek, all the while moving his skull to the reasonable cushion of his partner’s shoulder as he allows himself to relax as well.

“Next time, you’re coming to the Lab. I’m not dragging any of my equipment through Waterfall--not even for you.”

**Author's Note:**

> I have no clue about a backstory for how these two got together in an Underfell-like setting. (They're maybe too affectionate/personal for what's typical in Underfell.) The idea just revolved around the idea of “stress kills," and the fact that Fell!Grillby tends to be shown as a purple flame, burning hotter than the classic version.


End file.
